Projectile velocity and flight time

I am doing a computer course and we are using visual basic which is a programming program!

I am a hunter and also I am very interested in ballistics of rifles. I want to make a ballistics program using Visual basic but I am stuck on the projectile flight time and velocity.
Because if I have these two things I can work out bullet drop can I not?

I have made a sectional density calculator already that was quite simple.

I know that I need the muzzle velocity of the bullet which is easy, and I also need to know the ballistic co-efficient of a bullet, which I am also a little stuck on. Then I also I guess air drag comes into it which is different at different altitudes.